The present invention is directed to the manufacture of semiconductor devices and particularly to the manufacture of metallurgy for integrated circuit devices.
This invention relates to the formation of metallurgical interconnects for semiconductor devices, and particularly to the formation of contacts formed at the semiconductor surface which interface with metallurgy formed of copper-based metals. In the currently practiced process local interconnect trenches are etched into a first insulating layer deposited on top of a substrate having active devices. The etched trenches are filled with a liner/tungsten core to make contact with some portions of the substrate devices and polished to be coplanar with the first insulating layer to form the local interconnect (MC).
A second insulating layer is deposited and stud contact holes etched into it. The etched stud contact holes are filled with a liner/tungsten core and polished to be coplanar with a second insulating layer forming the stud contacts (CA) imbedded in the insulating layer which make contact with the local interconnect (MC) and also with additional portions of the devices. The first wiring level (M1) is then formed by either a deposition and subtractive etch or by a damascene process requiring a third layer. This M1 wiring level makes contact with the stud contacts (CA). While a preferred embodiment of the present invention is described using a tungsten local interconnect, the invention is not limited to use with this particular structure.
CA (stud contact) contact resistance is increasing as the technology moves from the 90 nm node to the 65 and 45 nm node. The present invention is directed to reducing this contact resistance. Another purpose of the present invention is to provide a more reliable contact.
These and other purposes of the present invention will become more apparent after referring to the following description considered in conjunction with the accompanying drawings.